Iodine supplements in pregnancy could boost children's IQ and save NHS funds
Scientists are urging pregnant and breastfeeding women to consider iodine supplementation to improve health, boost brain power and even save the NHS money in the long-term.
A study, published yesterday in The Lancet Diabetes & Endocrinology, found that maternal iodine deficiency is clearly associated with impaired child cognition and that pregnant and lactating women need more of the mineral during pregnancy and breastfeeding.
The increased dietary requirement among this group is already recognised and reflected in nutritional recommendations from the European Food Safety Authority and the World Health Organization (WHO). However, while this advice is incorporated into advice given out to pregnant women across much of the developed world, including Australia and the United States, UK dietary reference values have not been updated since 1991.
Dr Louis Levy, head of nutrition science, diet and obesity at Public Health England told the BBC: "The longstanding government advice is that everyone including pregnant women should be able to get all the iodine they need from a varied and balanced diet."
While the health problems associated with serious iodine deficiency, such as cretinism, a condition characterised by severe mental impairment, and goitre, a visible growth on the thyroid gland, are well-known, the effects of mild to moderate deficiency - as is emerging among the UK population - have previously been less understood.
A previous study, published in 2013, looked at the iodine levels of pregnant women in England, 67% of which were found to be mildly to moderately deficient. Researchers from Surrey and Bristol universities found that lowered iodine levels during the first trimester of pregnancy resulted in lowered IQ scores among those children. Samples and data of 1,040 women from longitudinal research project the Avon Longitudinal Study of Parents and Children (ALSPAC), in which 14,000 women enrolled during pregnancy between 1991-92, were used.
Urine samples were examined and more than two-thirds of these women were categorised as iodine deficient. Children born to those mothers had their IQ scored aged eight and had their reading ability assessed at age nine and results were adjusted to counter external factors such as parent education and whether the children were breastfed. The findings revealed that the offspring of women placed in the iodine deficient group during their pregnancy were "significantly more likely" to have children with low scores relating to verbal IQ, reading accuracy and reading comprehension.
The 2013 findings triggered the most recent study, led by Professor Kate Jolly from the University of Birmingham, who has called for a "large scale look at the iodine status of pregnant women", however, this is said to be unlikely to happen due to ethical and cost restrictions.
In the paper, Costs and benefits of iodine supplementation for pregnant women in a mildly to moderately iodine-deficient population: a modelling analysis, published yesterday in The Lancet, Dr Jolly and her team calculated a forecast of the potential impact of supplementation of all women before conception, during pregnancy and for the duration of breastfeeding. Based on the assumption that two-thirds of women are currently mildly to moderately deficient, they estimate that universal supplementation could boost IQ in babies born to those mothers by an average of 1.22 points.
Knock-on economic benefits
Researchers also analysed evidence from 3161 other studies that examined economic benefits of higher IQ scores, eight in depth, which demonstrated a higher IQ is associated with better health in general, with a predicted NHS saving of £199 per pregnancy. A forecast benefit of £4,476 per child was also calculated, as a result of the higher earnings attached to the increased IQ.
Fish is a good source of iodine, but pregnant women are advised to limit consumption due to high mercury levels found in some fish.
How much iodine do I need?
WHO recommends a daily intake of 0.15mg a day, but this recommendation increases to 0.25mg for pregnant and breastfeeding women. Unlike some other vitamins, iodine is not produced by the body and must be consumed via the diet.
Dietary sources include fish, dairy products, (in the UK, supplements are given to dairy cows, which then passes into the milk) and ordinary table salt, which is iodized in developed and developing countries in an effort to prevent widespread deficiency. Globally, UNICEF estimates that 66% of households have access to iodized salt.
Some cereals also contain the mineral in very small quantities, however, with many people in the developed world opting to cut down or even cut out salt and dairy, this group of sources may no longer be sufficient.
Co-author of the 2013 study, Dr Sarah Bath, MRC Population Health Scientist Fellow, has stressed that kelp and seaweed supplements should not be used as a source of iodine, especially by pregnant women, as they can contain harmful amounts. She has also pointed out that some pregnancy supplements already contain iodine. The Association of UK Dieticians (BDA) has produced a fact sheet detailing the importance of iodine during pregnancy and breastfeeding, available here.
Why is iodine so important?
According to the World Health Organization (WHO), iodine deficiency disorder (IDD) is one of the main causes of impaired cognitive development in children. The mineral is essential for hormone production within the thyroid in order to regulate growth, brain development and metabolism.
Deficiency in adults can lead to tiredness, lethargy, depression, high cholesterol and, eventually, a condition known as goitre - swelling of the thyroid gland. In children, the WHO says IDD jeopardises mental health and brain development whereas severe deficiency in the womb can result in stillbirth, miscarriage, congenital abnormalities and mental impairment.
Since the early 1980s, WHO has been behind a drive to eliminate the disorder - the countries where IDD is considered a public health problem have been halved as a result of its work.
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